Buggy code:
public class PartnerLibraryView extends BaseViewWithHandlers < PartnerLibraryUiHandlers > implements IsPartnerLibraryView { @ UiField HTMLPanel partnerPanel ; LibraryView libraryView = null ; private static final String FOLDERID = "id" ; @ UiField LibraryStyleBundle libraryStyleUc ; private String unitListId = "" ; private static final String LIBRARY_PAGE = "partner-page" ; private CourseDo courseDo ; private String placeToken ; private static PartnerLibraryView . PartnerLibraryViewUiBinder uiBinder = GWT . create ( PartnerLibraryView . PartnerLibraryViewUiBinder . class ) ; interface PartnerLibraryViewUiBinder extends UiBinder < Widget , PartnerLibraryView > { } private static MessageProperties i18n = GWT . create ( MessageProperties . class ) ; public PartnerLibraryView ( ) { } @ Override public void loadPartnersPage ( String callBack , String placeToken ) { } @ Override public void setUnitList ( final ArrayList < PartnerFolderDo > folderList ) { if ( ( ( folderList . size ( ) ) == 0 ) && ( AppClientFactory . getCurrentPlaceToken ( ) . equals ( ASPIRE_EPACS ) ) ) { loadingPanel ( false ) ; getComingSoonText ( true ) ; } else { getComingSoonText ( false ) ; } setCourseImageData ( ) ; libraryView . getLeftNav ( ) . clear ( ) ; libraryView . getContentScroll ( ) . clear ( ) ; String folderId = AppClientFactory . getPlaceManager ( ) . getRequestParameter ( PartnerLibraryView . FOLDERID ) ; int j = 0 ; for ( int i = 0 ; i < ( folderList . size ( ) ) ; i ++ ) { if ( folderList . get ( i ) . getType ( ) . equalsIgnoreCase ( "folder" ) ) { PlayerDataLogEvents . triggerLibraryViewEvent ( folderList . get ( i ) . getParentGooruOid ( ) ) ; LibraryUnitMenuView libraryUnitMenuView = new LibraryUnitMenuView ( folderList . get ( i ) ) ; libraryView . getLeftNav ( ) . add ( libraryUnitMenuView ) ; if ( ( j == 0 ) && ( folderId == null ) ) { j ++ ; loadingPanel ( true ) ; libraryUnitMenuView . addStyleName ( libraryStyleUc . unitLiActive ( ) ) ; unitListId = folderList . get ( i ) . getGooruOid ( ) ; libraryView . getFolderTopicTitleLbl ( ) . setText ( folderList . get ( i ) . getTitle ( ) ) ; libraryView . getListAllBtn ( ) . addClickHandler ( new PartnerLibraryView . ListAllBtnClickHandler ( folderList . get ( i ) . getGooruOid ( ) ) ) ; setTopicListData ( folderList . get ( i ) . getFolderItems ( ) , unitListId , folderList . get ( i ) . getParentGooruOid ( ) ) ; } } } final Iterator < Widget > widgets = libraryView . getLeftNav ( ) . iterator ( ) ; int widgetCount = 0 ; while ( widgets . hasNext ( ) ) { final Widget widget = widgets . next ( ) ; final LibraryUnitMenuView libraryUnitMenuView = ( ( LibraryUnitMenuView ) ( widget ) ) ; final int finalWidgetCount = widgetCount ; libraryUnitMenuView . getUnitMenuItemPanel ( ) . addClickHandler ( new ClickHandler ( ) { @ Override public void onClick ( ClickEvent event ) { libraryView . getContentScroll ( ) . setVisible ( false ) ; loadingPanel ( true ) ; final Iterator < Widget > widgetsPanel = libraryView . getLeftNav ( ) . iterator ( ) ; while ( widgetsPanel . hasNext ( ) ) { widgetsPanel . next ( ) . removeStyleName ( libraryStyleUc . unitLiActive ( ) ) ; } widget . addStyleName ( libraryStyleUc . unitLiActive ( ) ) ; unitListId = libraryUnitMenuView . getUnitId ( ) ; libraryView . getFolderTopicTitleLbl ( ) . setText ( libraryUnitMenuView . getTitle ( ) ) ; <START_BUG> libraryView . getListAllBtn ( ) . addClickHandler ( new PartnerLibraryView . ListAllBtnClickHandler ( libraryUnitMenuView . getLibraryGooruOid ( ) ) ) ; <END_BUG> if ( finalWidgetCount == 0 ) { setTopicListData ( folderList . get ( finalWidgetCount ) . getFolderItems ( ) , unitListId , libraryUnitMenuView . getLibraryGooruOid ( ) ) ; } else { getUiHandlers ( ) . getPartnerChildFolderItems ( unitListId , 1 , libraryUnitMenuView . getLibraryGooruOid ( ) ) ; } } } ) ; widgetCount ++ ; } } @ Override public void setTopicListData ( ArrayList < PartnerFolderDo > folderListDo , String folderId , String libraryGooruOid ) { } private void setCourseImageData ( ) { } private CourseDo getPartnerName ( ) { } public Map < String , LoadBannerActionInterface > addAllPartnerLibraries ( ) { } @ Override public void loadingPanel ( boolean isVisible ) { } @ Override public void getComingSoonText ( boolean isVisible ) { } @ Override public void clearPanels ( ) { } private static class AutodeskBanner implements LoadBannerActionInterface { private static PartnerLibraryView . AutodeskBanner autodeskBannerInstance ; private CourseDo libCourseDo ; private AutodeskBanner ( ) { } public static PartnerLibraryView . AutodeskBanner getAutodeskInstance ( ) { } @ Override public void loadLibBanner ( CourseDo courseDo , ThumbnailDo thumbnailDo , LibraryUserDo libraryUserDo ) { } @ Override public CourseDo getUpdatedCourseDo ( ) { } } private static class ONRBanner implements LoadBannerActionInterface { private static PartnerLibraryView . ONRBanner ONRBannerInstance ; private CourseDo libCourseDo ; private ONRBanner ( ) { } public static PartnerLibraryView . ONRBanner getOnrInstance ( ) { } @ Override public void loadLibBanner ( CourseDo courseDo , ThumbnailDo thumbnailDo , LibraryUserDo libraryUserDo ) { } @ Override public CourseDo getUpdatedCourseDo ( ) { } } private static class NgcBanner implements LoadBannerActionInterface { private static PartnerLibraryView . NgcBanner ngcBannerInstance ; private CourseDo libCourseDo ; private NgcBanner ( ) { } public static PartnerLibraryView . NgcBanner getNgcInstance ( ) { } @ Override public void loadLibBanner ( CourseDo courseDo , ThumbnailDo thumbnailDo , LibraryUserDo libraryUserDo ) { } @ Override public CourseDo getUpdatedCourseDo ( ) { } } private static class FteBanner implements LoadBannerActionInterface { private static PartnerLibraryView . FteBanner fteBannerInstance ; private CourseDo libCourseDo ; private FteBanner ( ) { } public static PartnerLibraryView . FteBanner getFteInstance ( ) { } @ Override public void loadLibBanner ( CourseDo courseDo , ThumbnailDo thumbnailDo , LibraryUserDo libraryUserDo ) { }

Fix:
libraryView . getListAllBtn ( ) . addClickHandler ( new PartnerLibraryView . ListAllBtnClickHandler ( libraryUnitMenuView . getUnitId ( ) ) ) ;